global category thumbnails

Rather then just a list of links for this global categories page, is there a plugin or some coding solution that allows me to associate a thumbnail image with each product category?

http://www.ybrmarket.com.au/product-categories/

im using the page template and this shortcode to get what i have now. But i really need some thumbnails associated with the categories.
echo do_shortcode('[mp_global_categories_list order_by="name" order="ASC" paginate=false per_page="40"]');

I dont want to resort to hardcoding.
I am using the featured image for all products.

http://www.ybrmarket.com.au/product-categories/